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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.IMastro-ph.COastro-ph.GA

Visual analytics for cosmological simulation results

Paul Vauterin, Maarten Baes

Context: Modern cosmological simulations rely on sophisticated assumptions and generate rich, highly complex datasets. Interpreting their results in order to extract new scientific insights remains challenging. Existing visualisation tools offer powerful capabilities but often come with a relatively high barrier for entry, and are not designed with a focus on knowledge discovery through real-time, intuitive visual analytics. This stands in contrast to other research domains, such as bioinformati…

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astro-ph.COastro-ph.GA

Planck Constraints on Turbulence in the Coma Cluster

Baptiste Sigal, Etienne Pointecouteau, Nicolas Clerc, Simon Dupourqué, Alexeï Molin, François Mernier, Rémi Adam, Tanguy Dusserre et al.

Turbulence within the intracluster medium (ICM) influences galaxy cluster thermodynamics and virialisation, contributing to non-thermal pressure support and impacting hydrostatic mass estimates. Characterising this turbulence through thermodynamic fluctuations remains observationally challenging due to the non-linear relationships between observables such as density and pressure, and the underlying velocity field. This study aims to constrain the properties of ICM turbulence by performing a comp…

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astro-ph.GA

Recovering pattern speeds of simulated face-on barred galaxies via Schwarzschild modelling

Iliya S. Tikhonenko, Jens Thomas, Roberto P. Saglia

Stellar bars are a major driving force in the secular evolution of their host galaxies. To better understand the connections between the 3D bar density structure, its orbital composition, stellar populations, and underlying dark matter distribution, it is desirable to construct detailed dynamical models of barred galaxies. However, only a few external barred galaxies have been studied in this way so far. We present a new Schwarzschild orbit superposition code for triaxial potentials with figure…

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astro-ph.IMastro-ph.GAastro-ph.SR

The critical role of HST UV spectroscopy in constraining red supergiant binary systems

Daniel Jadlovský, Andreas Sander, Lee Patrick, Jiří Krtička, Gemma González-Torà, Matheus Bernini-Peron

The Hubble Space Telescope (HST) has advanced our knowledge of stellar evolution thanks to its unique high-spectral resolution and high-sensitivity capabilities in the UV region, especially for hot massive stars. Within the field of red supergiants (RSGs), it has led to several major insights as well, such as, for example, characterizing the embedded hot companion in the VV Cephei system, the detection of surface mass ejection from Betelgeuse, and unveiling the rich population of RSG+B binaries…

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hep-phastro-ph.IMgr-qchep-ex

Halbach Magnetic Weber Bars

Valerie Domcke, Itay M. Bloch

Magnetic Weber Bars have been proposed to search for gravitational waves in the kHz to GHz regime by exploiting the mechanical deformation of a large magnet induced by a gravitational wave. Here we propose to increase the effectiveness of such devices by considering magnetic field configurations with strong gradients, albeit lower field strengths, such as Halbach arrays. We focus on one of the most challenging but most realistic signals, with short duration and low coherence, exploiting the ring…

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astro-ph.EP

Gas Phase Ion Species Released During Grain Collisions: Implications For Protoplanetary Disks

Patrick Hock, Gerhard Wurm

Grain charging and gas ionization are important processes in protoplanetary disks. Both occur in mutual collisions between grains, as charge is exchanged between grain surfaces but also released into the surrounding gas as ions. The charge carrier for tribocharging, the origin of the gaseous ions, and their composition are currently unknown. However, it is important to know to validate the significance of these processes under disk conditions. In this work, we approach these questions by detecti…

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gr-qcastro-ph.EPastro-ph.SR

Deviation of trajectories in nonrelativistic and relativistic cases and Shirokov effect

Yu. V. Pavlov, V. P. Vandeev

We compare the deviations of circular orbits in the nonrelativistic and relativistic cases. General solutions of the deviation equations are obtained. We find the potentials for the nonrelativistic case and the metric components in general relativity for which trajectories close to circular ones are closed curves. Explicit expressions for the pericenter shift of an orbit close to a circular one in a static spherically symmetric spacetime are obtained. Estimates of the cosmological constant effec…

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astro-ph.IMphysics.opticsquant-ph

Information limits of photonic lantern wavefront sensing: a Fisher- and quantum-Fisher-information framework and its relation to Fourier-filtering sensitivity limits

Kalaga Madhav

The photonic lantern is an all-photonic wavefront sensor native to single-mode-fibre-fed instruments, but its performance is almost always quoted through a specific reconstruction algorithm, obscuring how much wavefront information the device itself encodes. We develop, from first principles, the Fisher-information and Cramer-Rao theory of the photonic-lantern wavefront sensor, benchmark it against the quantum Cramer-Rao bound via an explicit multi-parameter quantum-Fisher-information calculatio…

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astro-ph.IM

Maximising the mid-infrared high-contrast performance of ELT/METIS despite water vapour seeing

Olivier Absil, Gilles Orban de Xivry, Prashant Pathak, Abhirami S. Raghu, Benjamin Courtney-Barrer, Roy van Boekel, Thomas Bertram, Markus Feldt et al.

The Mid-infrared ELT Imager and Spectrograph (METIS) will be equipped with a SCAO system delivering Strehl ratios above 90% at L band (3.5 - 4.1 um) and close to 99% at N band (8 - 13 um) on bright stars. Yet, the actual wavefront quality seen by the METIS coronagraphic modules used for high-contrast imaging will be significantly affected by water vapour seeing, which add a strong chromatic component to dry air seeing in the mid-infrared. We analysed two years of VLTI/GRAVITY fringe tracker arch…

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astro-ph.SR

Spectroscopy of flares on AU Mic

P. Odert, M. Leitzinger, P. Kabáth, R. Greimel, J. Lipták, R. Karjalainen, P. Heinzel, J. Wollmann et al.

Photometric space missions like Kepler and TESS have revealed unprecedented statistics of stellar flares, including the frequent detection of highly energetic superflares. Spectroscopic characterization of flares and especially superflares, however, is still not as commonly available. In contrast to broad-band photometry, spectroscopic data can give more insights into the physical parameters of flares, as well as allowing to identify possibly accompanying CMEs. In this context, we monitored the…

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astro-ph.SR

Spectroscopic investigation of the southern late-K/early-M dwarf binary CC Eri

M. Leitzinger, P. Odert, R. Greimel, P. Kabáth, J. Lipták, R. Karjalainen, P. Heinzel, J. Wollmann et al.

In the recent past investigations of stellar Coronal Mass Ejections (CMEs) and flares/superflares gained special attention because of their relevance for planetary habitability and stellar evolution. With respect to that, we present an observing campaign at the ESO152 telescope on LaSilla operated by the PLATOSpec consortium of the late-K/early-M dwarf binary CC Eri. The ESO152 telescope is currently equipped with an Echelle spectrograph which enables the investigation of a broad spectral range,…

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astro-ph.GA

The Radial Acceleration Relation in Galaxies and Clusters from a Two-Component, Virial-Motivated Framework

Christine C. Dantas, Andre L. B. Ribeiro, Hugo V. Capelato

We present a comparative analysis of acceleration data for gravitational systems drawn from multiple observational sources, including: (i) early-type galaxies (ETGs) (Lelli et al. 2017); (ii) Brightest Cluster Galaxies (BCGs) and galaxy clusters (Tian et al. 2020, 2024); and (iii) weak gravitational lensing of isolated galaxies (Brouwer et al. 2021; Mistele et al. 2024). These data are interpreted within a framework motivated by the Two-component Virial Theorem (2VT), which defines a global bary…

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astro-ph.IM

Liquid nitrogen pre-cooling system for ELT instruments utilizing additively manufactured heat exchangers, integrated temperature and liquid level control

Anastasios Aretos, Younes Chahid, Lee Chapman, Mark Cliffe, Maia Jones, Scott McPhee, Chris Miller, Graham Wilks et al.

Using liquid Nitrogen as the cryogenic fluid for pre-cooling purposes is almost ubiquitous across modern observatories. That method tends to be inefficient since it relies on the evaporation of the fluid afforded by the available surface area within the exchanger without capturing any of its latent heat. An additively manufactured heat exchanger could address that inefficiency by providing an increased evaporation area as well as internal structures that can interact with Nitrogen in its gaseous…

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astro-ph.SRphysics.ao-phphysics.flu-dyn

Turbulent Convection: Modal Equations and Energy Pathways

S. Sridhar, Nishant K. Singh

We present a framework for studying high Rayleigh number turbulent convection to better understand stellar and planetary convection zones. Utilizing the statistical symmetries of the fully developed turbulent state of Boussinesq convection, we identify relevant mean and fluctuating quantities. After validating these symmetry assumptions through numerical simulations, we formulate the governing equations. Vertical profiles of key physical quantities in the saturated turbulent state are explored i…

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astro-ph.HEgr-qc

Spectral densification and macroscopic phase delay of gravitational echoes from exotic compact objects

Corentin Guigot

Gravitational-wave echoes from Exotic Compact Objects (ECOs) provide an observable probe for horizon-scale physics. Standard phenomenological models for these signals typically assume a constant Free Spectral Range, relying on the geometric optics approximation. In this work, we demonstrate that wave dispersion at the photon sphere induces a systematic deviation from this assumption, manifesting instead as a hyperbolic spectral densification. By employing an analytical framework based on the Ric…

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hep-phastro-ph.HEhep-ex

Rare processes in ultrahigh-energy tau-lepton transport

Guo-yuan Huang

In cosmic neutrino observatories, charged-lepton transport is a key input for interpreting observables and reconstructing neutrino events. Charged leptons propagating through matter undergo several energy loss processes, such as electron pair production and photonuclear interaction. In this work, we investigate several rare processes in tau-lepton transport, focusing primarily on muon pair production, $τN \to τμ^+μ^- N$, and Primakoff neutral-pion production, $τN \to τπ^0 N$. At EeV energies, we…

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astro-ph.IMastro-ph.SRphysics.space-ph

The CUSP CubeSat mission for space weather multi-physics analysis, design, and testing

Giovanni Lombardi, Riccardo Di Spirito, Sergio Fabiani, Daniele Censi, Giovanni De Cesare, Ettore Del Monte, Riccardo Campana, Enrico Costa et al.

The CUbesat Solar Polarimeter (CUSP) mission aims to measure the linear polarization of solar flares in the hard X-ray band by means of a Compton scattering polarimeter. CUSP is a project in the framework of the Alcor Program of the Italian Space Agency aimed at developing new CubeSat missions. We present the outcomes of the CUSP's Phase B study, which is ended on 2 July 2026. The design solutions adopted for the mission's most critical multi-physics design drivers will be discussed, these solut…

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astro-ph.SR

Pulsations along the Asymptotic Giant Branch (AGB): a global view

Pierre Darriulat, Pham Thi Tuyet Nhung, Do Thi Hoai

In three preceding articles, we studied the relation between the light curves of Mira variables and their stellar properties. The analysis was restricted to a sample of stars offering high density and quality of observations in the visible, allowing for the definition of simple parameterizations of the light curves. Clear relations were revealed between the evolution of the stars along the AGB and parameters such as the width of the light pulse or the deviation of its ascending branch from a sin…

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astro-ph.HEastro-ph.IM

Joint X-ray and gamma-ray analysis at the photon level: Application to MSH 15-52

Katharina Egg, Alison M. W. Mitchell

Joint analysis of multi-wavelength (MWL) data at the level of photon events is challenging, but it provides a statistically preferable method of fitting the data, in contrast to fitting derived flux points. Data from X-ray and gamma-ray instruments are well-suited for a joint description, due to their common physical origin (same particle population and non-thermal processes) and incidentally also due to the high similarity of their formats. Such a description is especially desirable for objects…

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astro-ph.EPastro-ph.SRphysics.flu-dyn

Tidal dissipation in magnetised, rotating stars and planets: linear calculations exploring various magnetic field configurations

Shijun Chu, Zhao Guo, Aurélie Astoul, Adrian J. Barker, Rainer Hollerbach

We study tidal flows in the convective envelopes of rotating, magnetised fluid bodies, such as low-mass stars and giant planets. In well-mixed convective regions, (magneto-)inertial waves are linearly excited by tidal forcing, and their dissipation can dominantly drive spin and orbital evolution in many close star-planet and binary star systems. We perform linear magnetohydrodynamic calculations of wavelike tides in spherical-shell geometry of a tidally-forced, rotating, incompressible, viscous…

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astro-ph.HE

Polar cap plasma loading and the morphology of pulsar $γ$-ray light curves

Jérôme Pétri

The discovery of more than 300 $γ$-ray pulsars by the Fermi Large Area Telescope (Fermi-LAT) has revealed a rich diversity of light-curve morphologies that remains challenging to reproduce within purely magnetospheric emission models, suggesting that particle acceleration and radiation may occur, at least in part, in the striped-wind current sheet. We compute a comprehensive atlas of pulsar $γ$-ray light curves based on the split-monopole current sheet geometry, with the goal of quantifying the…

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astro-ph.HE

Optical Images of the Braneworld Black Hole Surrounded by an Optically Thin Accretion Disk

Wen-Hao Deng, Sen Guo, Qing-Quan Jiang, Kai Lin, Pei Wang

This work examines the observational signatures of rotating black holes with tidal charge in the Randall--Sundrum braneworld scenario. Combining an elliptic-integral-based analytical treatment with numerical ray tracing, we characterize photon motion around braneworld black holes in detail. For small observer inclinations, secondary images remain embedded inside the primary emission rings. As the inclination becomes larger, the primary and secondary images gradually separate and produce a strong…

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astro-ph.IM

HARMONI at ELT: Developing a Modular Review Process using TRIZ

Amelia Calderhead, Anna MacIver, David Isherwood, Andy Born, James Stevenson

HARMONI is the first light, adaptive optics assisted, near-IR integral field spectrograph for the ELT. It covers a spectral range from 800nm to 2450nm with resolving powers from 3000 to 7000 and spatial sampling of 25mas and 6mas. It can operate in two adaptive optics modes - SCAO (including a high contrast capability) and MCAO. The project is resuming its final design phase after a rescope design phase in 2025. The HARMONI team at UKATC have been pioneering the use of TRIZ by managing monthly T…

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astro-ph.GAastro-ph.HE

Reincarnations of massive stars in active galactic nucleus discs

Jing-Tong Xing, Tong Liu, Jiao-Zhen She

The origin and evolution of massive stars in active galactic nucleus (AGN) discs remain uncertain. We develop a semi-analytical model that follows the evolution of an embedded core-collapse supernova (CCSN) remnant and the subsequent formation and growth of a compact gas cloud. In the dense disc environment, efficient radiative cooling can strongly compress or bypass the Sedov-Taylor stage and drive the remnant rapidly into radiative snowplow evolution. After the remnant loses its interior press…

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astro-ph.EP

A Physically Driven Parameterisation of Multidimensional Atmospheres: Application to the JWST Phase Curve of WASP-121b

Yuanheng Yang, Guo Chen, Xianyu Tan, Thaddeus D. Komacek, Xi Zhang, Thomas M. Evans-Soma, Fei Yan, Chengzi Jiang et al.

Understanding the multidimensional structure of strongly irradiated exoplanets is essential for interpreting their atmospheric dynamics, chemistry and energy transport, yet current analyses remain limited by the difficulty of extracting reliable phase-resolved spectra and by the lack of physically interpretable parameterisations for retrievals. We combine a data-driven eclipse-normalisation method with an analytical three-dimensional temperature parameterisation derived from radiative, advective…

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astro-ph.GAastro-ph.SR

The Open Cluster Chemical Abundances and Mapping Survey XI. First Gradients from SDSS/MWM BOSS Determined Clusters

Jonah M. Otto, Peter M. Frinchaboy, John Donor, Ilija Medan, Natalie R. Myers, Audrey Hauck, Katia Cunha, Gail Zasowski et al.

The Milky Way Mapper program in the fifth generation of the Sloan Digital Sky Survey (SDSS-V/MWM) has observed millions of stars, thousands of them in open clusters. The Open Cluster Chemical Abundances and Mapping (OCCAM) survey continues to create comprehensive datasets of open clusters and their members in order to constrain Galactic parameters. This eleventh contribution from the OCCAM survey is the first to use stellar parameters from stars observed with the optical Baryon Oscillation Spect…

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astro-ph.EPastro-ph.SR

Asymmetric, variable H$α$ line profile in planetary mass object SR 12 c

Jun Hashimoto, Yuhiko Aoyama, Michihiro Takami, Shinsuke Takasao

Young, forming planetary-mass objects often exhibit clear signatures of ongoing mass accretion and are thought to accrete material through processes analogous to those operating in young stars. In this study, we present high-spectral-resolution observations of asymmetric and time-variable H$α$ line profiles from the planetary-mass companion SR~12~c. The H$α$ line was observed at a resolving power of $R \sim 49,000$--40{,}000 (corresponding to 6.1--7.5~km~s$^{-1}$) using the High Dispersion Spect…

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astro-ph.SRphysics.atom-ph

A New Approach to Modeling Line Shapes with Quasi-H$_2^+$ Satellites in Stellar Atmospheres

Jackson R. White, Thomas A. Gomez, Mark C. Zammit, Michael H. Montgomery, Bart H. Dunlap, Ivan Hubeny, Dmitry V. Fursa, Igor Bray et al.

Theoretical spectral line shapes describe the distribution of opacity due to bound electronic transitions in hot dense plasmas and are used to fit emergent spectra from many astrophysical sources. Deficiencies in line broadening theory have been proposed as a possible explanation for unresolved discrepancies between theoretical and observed spectra in white dwarf star atmospheres and laboratory experiments at white dwarf star photosphere conditions. One possible source of these discrepancies is…

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astro-ph.HE

Strongly Magnetized Super-Eddington Accretion: How Spin and Accretion Rate Regulate Energy Output and Mass Loss

Tom Man Kwan, Lixin Dai, Cheuk Kwan Kan, Zepei Xing, Tassos Fragos, Matthew Middleton, Tao Ji, Feng Yuan et al.

Strongly magnetized super-Eddington accretion flows power many important astrophysical systems, but how black hole parameters control their output is unclear. We present 32 general relativistic radiation magnetohydrodynamics simulations of super-Eddington magnetically arrested disks onto stellar-mass black holes, varying mass ($M_{\rm BH}= 5, 15, 30\,M_{\odot}$), spin ($a=0,0.9$), and accretion rate ($\dot{M}_{\rm acc} \approx 1-2000\,\dot{M}_{\rm Edd}$). We find that black hole spin and accreti…

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astro-ph.IM

On-sky results from REDWOODS, a platform at Lick/ShaneAO for testing second stage AO technologies

Benjamin L. Gerard, Dominic F. Sanchez, Aditya R. Sengupta, Chris Ratliff, Sylvain Cetre, Elinor Gates, Daren Dillon, Bautista Fernandez et al.

REDWOODS is a new sub-testbed within the Shane Adaptive Optics (AO) system at Lick observatory, developed to test second stage AO wavefront sensing and control technologies, including a Self-Coherent Camera with optional broadband Wynne corrector, two different three-sided fully reflective highly broadband pyramid wavefront sensor modes, and multi-wavefront sensor single conjugate AO control. We present project results to date, including on-sky data.

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